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Holographic Grating Relaxation Studies of Probe Diffusion in Amorphous Polymers
NEBRASKA UNIV LINCOLN DEPT OF CHEMISTRY
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Probe diffusion of camphorquinone, thymorquinone and diacetyl is studied by the laser induced holographic grating relaxation HRG technique in polymers. It is shown that the probe diffusion coefficient decreases as the probe size increases. The presence of plasticizer enhances the rate of probe diffusion whereas crosslinker retards the diffusion. Probe diffusion is also studied by varying of polymer properties such as Tg, molecular weight and chain conformation. Temperature dependent studies show that except for the very low molecular weight polymethylmethacrylate, all diffusion coefficients fit well to the WLF equation. Probe diffusion of camphorquinone is found to be much slower in polyvinyl acetate than in other polymers. This result is correlated with the outstanding damping property of the polymer. Probe diffusion, Holographic grating relaxation, Chromophore diffusion in PS, PMMA, PVAc, Polybutadiene, Polyethylmethacrylate effects of glass transition, Chain branching.
APPROVED FOR PUBLIC RELEASE